This invention relates generally to the diagnostic evaluation of the urinary tract. More particularly, this invention relates to urethral profilometry, and an improved method for generating a urethral pressure profile.
Malfunction of the complex urinary tract can result in a variety of objectionable and unfortunate problems. One of the most common problems associated with urinary dysfunction is incontinence, or the inability to volitionally control micturition. One technique for investigating urinary dysfunction is cystometry. Cystometry measures vesical innervation and the elastic characteristics of the bladder wall. The cystometrogram which is generated by the latter process correlates internal bladder pressure with a volume of fluid injected therewithin. Another urinary investigative technique is electromyography, in which the electrical responses of the sphincters are monitored and displayed. The latter two techniques, as well as background material relevant to cystometry, electromyography and profilometry techniques, are discussed in a co-pending patent application entitled Method and Apparatus for Performing Micturition Analysis, filed on Apr. 7, 1975 bearing Serial No. 566,044, now U.S. Pat. No. 4,063,548, which is owned by the same assignee as in the instant case and is hereby incorporated by reference.
Profilometry, the urinary diagnostic technique most relevant to the instant invention, involves the generation of a urethral pressure profile. The urethral pressure profile is a graphical record of pressure within the urethra at successive points along its length. It is known that continence will be maintained if the intraurethral pressure is greater than the intravesical pressure. Leakage of urine occurs when urethral pressure decreases to less than bladder pressure. The utility of the urethral pressure profile as a diagnostic technique is thus indicated.
In the prior art urethral pressure profiles have been generated by retrograde installation of fluid into the urethra until the pressure was sufficient to overcome the sphincter resistance thereby forcing fluid into the bladder. Fluid filled pressure balloons have been utilized as a method of measuring urethral pressure, but such apparatus has a disadvantage of measuring pressure over a finite length of the urethra, equivalent to the length of the balloon rather than pressure at consecutive points. Another technique involves the insertion of a catheter internally of the urethra, and the subsequent measurement of urethra pressures along the length of the urethra as the catheter is withdrawn. By graphically displaying the results on a strip chart, for example, a correlation of urethral pressure versus position within the urethra will be provided. Usually the catheter is withdrawn mechanically, although manual withdrawal has been practiced. Various urethral pressure profile systems are discussed in the British Journal of Urology, Vol. 46, pages 325 to 336 (1974); Urology, Vol. 5, No. 5, May, 1975, page 632; and Urological Research, Vol. 1, pages 97-100 (1973).
Other pertinent U.S. patent references relevant to the instant invention are as follows:
U.S. Pat. No. 3,897,682, issued Aug. 5, 1975 to A. E. Brooks; PA0 U.S. Pat. No. 3,628,538, issued Dec. 21, 1971 to Vincent et al.; PA0 U.S. Pat. No. 3,641,993, issued Feb. 15, 1972 to Gaarder et al.; PA0 U.S. Pat. No. 3,774,593, issued Nov. 27, 1973 to Hakata et al.; PA0 U.S. Pat. No. 3,815,611, issued Nov. 26, 1971 to R. H. Denniston; PA0 U.S. Pat. No. 3,674,010, issued July 4, 1972 to J. Falenks; PA0 U.S. Pat. No. 3,437,088, issued Apr. 8, 1969 to L. J. Bielinski; PA0 U.S. Pat. No. 3,870,072, issued Mar. 11, 1975 to H. Lindemann.
When a urethral pressure profile has been generated, those areas within the urethra which are unable to maintain the correct pressure will be identified by characteristic graphical inflections. Since successive points along the urethra will be identified along the horizontal axis of the graph, those portions of the urethra requiring further investigation will be diagnostically exposed. Thus the urethral pressure profile technique provides a valuable diagnostic aid.
It is also known that the urethra produces a variety of electrical signals which may be analyzed to provide useful diagnostic information. The functioning of sphincter muscles, for example, can be investigated through the process of electromyography as described in the above-mentioned co-pending patent application. It is thus advantageous to derive urethral electrical signals during generation of a urethral pressure profile.